1. Technical Field
The present invention relates to a carton having a barrier construction and a method of making the same which is to be filled with a consumable product accessible through an opening in the carton. More particularly, the invention pertains to a carton which when sealed forms a resistant barrier between the contents thereof and the surrounding environment.
2. Background Art
Paperboard cartons have been manufactured with a variety of constructions and opening features which allow the consumer access to the contents of the carton. Many of these constructions, however, are not concerned with the effects of the environment on the consumable product contained within the final carton. Additionally, the opening features which may consist of perforations, herringbone cuts, adhesive weaknesses, as well as other means of providing a point along the top panel, side panel or hinge lines where the carton may be most readily opened or similarly unconcerned about the detrimental affects of the environment on the contents of the carton.
U.S. Pat. No. 3,399,820 issued to Foster et al. discloses one such opening feature commonly employed in cartons of this type. This opening feature is what is known as a double cut score opening feature which is formed by way of double cut scores; i.e., a pair of inner and outer cuts in the paperboard material with the cuts of each pair running parallel to one another, along a panel of the carton. By so providing these cut score lines, when the consumer applies an upward force or opening force on the tear flap provided between the pairs of cut score lines, ply separation occurs in the region between the inner and outer cut score lines. Continued pulling of the tear causes complete separation of the opening flap to allow the consumer unobstructed assess to the contents of the carton.
Similar opening features are disclosed in U.S. Pat. No. 4,746,109 issued to Prater and U.S. Pat. No. 4,613,046 issued to Kuchenbecker. As in the above-mentioned patent, a point of weakness is provided in a panel of a respective carton where ply separation of the panel is permitted to occur when the consumer applies an opening force to the pull tab. The ply separation occurs between two pairs of reverse cut lines which are formed at least halfway through the panel of the carton area. However, when forming the paperboard blanks which are to be later used and erecting the cartons disclosed, both sides of the paperboard material are cut approximately 50% of the paperboard thickness into the carton. By cutting through both sides of the paperboard carton, the barrier which may have previously existed due to various coatings provided on the paperboard is reduced. By cutting into both sides of the paperboard, there is left only the plies of the paperboard material which are not impervious to moisture and subsequently cannot prevent the leaking of moisture into and out of the carton. Moreover, the construction of the above-mentioned cartons results in the exposure of bare edges of paperboard material within the internal cavity of the erected carton. By presenting such exposed paperboard edges within the cavity of the formed carton will allow wicking to occur as with the double cut score feature which in time could result in contamination of the contents of the container or leakage of the contents from within the container.
U.S. Pat. No. 4,687,104 issued to Ielmini discloses a similar carton construction having double cut scores formed on the inner and outer surfaces of the top and front flaps thereof. Again, as with the previous constructions, by cutting through both sides of the paperboard carton, the barrier which may have previously existed due t the various coatings provided on the paperboard material would be eliminated, thereby resulting in possible contamination of the contents of the carton or leakage of such contents. Additionally, as with the previously mentioned constructions, bare edges of the paperboard material will be exposed within the cavity of the formed carton thereby resulting in the possible contamination or leakage of the contents of the carton.
In an attempt to overcome the shortcomings associated with the above-described carton construction, cartons of the form known in the art has bag-in-a-box type constructions where developed. One such carton is illustrated in U.S. Pat. No. 3,580,466 issued to Thelen et al. wherein a bag formed of a plastic or treated paper material is positioned within the carton prior to its final sealing procedures. The carton may be formed having the double cut score opening feature; however, because the contents are enclosed within the plastic bag within the carton, the contents thereof are not exposed to any environmental affects nor is it possible for the contents of the bag to leak from the carton. However, such construction adds significantly to the cost of the carton, as well as the manufacturing process entailed in forming the final product.
U S. Pat. No. 4,951,824 issued to Kuchenbecker et al. discloses one solution to the aforementioned problem of leaking in the top panel of the formed carton at the region of weakness necessary for forming the opening feature. Therein, the inner line of weakness is formed by way of a crease score line rather than a partially cut score line such that the integrity of the inner surface f the top panel is maintained. However, the overall construction of the carton when erected results in the exposure of bare edges of the carton blank within the inner cavity of the carton. Again, as mentioned above, this may result in the contamination of the contents of the carton or leakage of the contents therefrom.
Therefore, as can be seen from the foregoing, there is clearly a pressing need for a carton of the above-mentioned type which will provide a reliable opening feature that is capable of opening with ease by the consumer, which will resist the infiltration of moisture and will not retard the structural integrity of the carton when opened. Moreover, there is a pressing need for a carton having a construction which does not result in the exposure of bear paperboard edges within the inner cavity of the carton, thus eliminating any potential of leakage of the contents or contamination thereof.